Innocuous rocks in regular light become something special when lit by ultraviolet rays.

The rocks were part of the third annual Sample's Agate Gem and Mineral Shop's Agate Show Saturday, Jan. 5, at the Northland Arboretum.

"The first two shows were held at home," said Alex Sample of the annual show. After moving this year's show to the Northland Arboretum, Sample said: "we went from 40 people to 500 plus in a year."

For this year's event, Erik Rintamaki of Michigan brought the glowing stones after his friend Sample invited him to come to his rock show in Brainerd. The coarse gray igneous rocks that look like granite are syenite with sodalite. It's the sodalite that causes the golden fluorescent glow.

Rintamaki had been looking for a new way to find agates and took a UV light to the beach on the shore of Lake Superior when he discovered stones with an orange glow. He didn't know what they were so he began to investigate.

"I go on Google, couldn't find anything about them on Google," Rintamaki said. "Went on Facebook, fluorescent mineral pages, nobody had any clue. Everybody kind of thought they were sodalite, but nobody really knew so I ended up getting them in the hands of scientists and they did a study on the stones, they took them to Michigan Tech University and used their scanning electron microscope and found out the fluorescent part of the stones is sodalite, so they are syenite rich in fluorescent sodalite."

Rintamake stated the syenite with sodalite was probably spread by glaciers from Canada so that means that apart from being found in the Upper Peninsula they could be in others areas with glacial activity. This was the first documented case of sodalite being found in Michigan, Rintamaki and Mineral News, a monthly publication based in Virginia, reported.

The name Yooperlites for the stones was coined by Rintamaki, after the place he found them, the Upper Peninsula of Michigan, a region whose inhabitants are locally known as "Yoopers" and "lite" for the glow the sodalite causes.

The agate show included about 14 vendors, food and door prizes with a chance to buy, sell and trade gems and minerals. The show will return for the first Saturday in 2020.